As a method of transmitting transmission data from a transmission device to a reception device, there is a method of opto-spatially transmitting the transmission data with light (in other words, an optical signal), for example. For example, Patent Literature 1 discloses a technology that merges the function of an optical signal transmitter with the backlight of a liquid crystal display, and opto-spatially transmits music data to headphones equipped with a dedicated receiver with light emitted from the liquid crystal display.